Hello,
Is your error on the $inputmailboxticket variable on line 7867?
If so, this error has been corrected and is now available via subscription service.
Have a nice day,

Hello
thank you for your reply.
yes these errors are related to the same variable.
thank you for your assistance

Hello
thank you for your reply ythe exact error is :
Error on SqlElement to get 'manual' for Class 'Assignment' field 'manual' not found in Database.
Thanks for your help and assistance

Hello,
Have you installed sql scipts from the projeqtor_V12.1.O.sql version? (if you haven't, don't!)
What php version are you on?
In your database, the assignment table has ‘isManual’ instead of ‘manual’?

Hello,
after checking we have installed 12.02 than upgarded to 12.1 after finding some issues in 12.1 we downgraded to 12.02 again .
the adatbase exists from a long time we did not installed it with scripot of 12.1
php version 8
I hope my ansewrs gave you a clear idea about the problem.
  

Hello,
So it's normal that we've changed some things in the database, in particular the assignment table with isManual instead of manual to be compatible with the new version of php
ALTER TABLE `${prefix}assignment` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
run this line on your database > ALTER TABLE `${prefix}assignment` CHANGE `isManual` `manual` int(1) unsigned DEFAULT '0' COMMENT '1';

The following lines may also lead to other errors
ALTER TABLE `${prefix}work` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
ALTER TABLE `${prefix}plannedwork` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';
ALTER TABLE `${prefix}plannedworkbaseline` CHANGE `manual` `isManual` int(1) unsigned DEFAULT '0' COMMENT '1';

Hi

To complete maxca's answer, 
downgrading version would require to restore DB before migration.

So advised step of migration :
- backup DB
- migrate
- test
If test are not correct and you need to downgrade
- downgrade
- restore backup

Thank you for your help and assistance. Now since 12.1.1 is the stable versuion we could moove to 12.1.1 safely.